Damaged olives hang in the grove belonging to Augusto Spagnoli, an oil producer from Nerola, near Rome. Producers and experts declared Italy's 2014 olive harvest the worst in history, due to adverse climatic conditions that helped the olive fly proliferate, thus destroying the olives before they could be harvested. Alessandra Tarantino/AP hide caption

itoggle caption Alessandra Tarantino/AP

Experts say lots of factors determine how quickly an oil deteriorates — from the variety of the olives, to how the oil is produced and stored. Matthias Schrader/AP hide caption

itoggle caption Matthias Schrader/AP

Palestinian women harvest olive trees near the occupied West Bank village of Deir Samet near the town of Hebron. Hazem Bader/AFP/Getty Images hide caption

itoggle caption Hazem Bader/AFP/Getty Images

A Greek farmer drives home with his fresh pressed olive oil in barrels near Alyki, Greece. The country's pure olive oil is hard to find, expensive and poorly marketed, businessmen say. Matthias Schrader/AP hide caption

itoggle caption Matthias Schrader/AP